1. Field of the Invention
The present invention relates to a vibration wave motor and a lens barrel including the vibration wave motor.
2. Description of the Related Art
In general, a vibration wave motor used for a driving unit includes a vibrator (vibration body) having an energy transducer, such as a piezoelectric device, and a contact body in contact with the vibrator. The vibration wave motor transduces kinetic energy caused by traveling waves or standing waves to a relative movement between the vibrator and the contact body using a frictional force. In such a structure, the output of the vibration wave motor is significantly influenced by the friction on an interface between the vibrator and the contact body and by the number of the vibrators. Accordingly, a variety of ultrasonic motors having various contact mechanisms of vibrators are proposed.
For example, Japanese Patent Application Laid-open No. 11-235062 discloses such a vibration actuator device (vibration wave motor). This vibration actuator device includes a vibrator that vibrates in accordance with a driving signal, a ring-shaped relative movement member in contact with the vibrator to relatively move, and a pressure support member that supports the vibrator and applies pressure to the vibrator so as to be in contact with the relative movement member. The pressure support member includes a ring-shaped base portion, a leaf spring supported by the base portion in a cantilever fashion, and a support portion provided at a free end of the leaf spring.